1. Field of the Invention
The present invention relates to a semiconductor device in which electrodes on a semiconductor chip are connected electrically to conductive wires on a wiring board via protruding electrodes (bumps), and to a method for manufacturing the same.
2. Description of the Related Art
A package such as a Bump on Film (BOF) used in LCD drivers and the like is known as a semiconductor device in which protruding electrodes (bumps) are formed on conductive wires on a wiring board and electrodes on a semiconductor chip are connected electrically to the conductive wires via the bumps. Tape carrier substrates in which wiring is formed on a film base material such as polyimide often are used as wiring boards for mounting semiconductor chips.
A semiconductor device disclosed in JP 2004-327936A is described below with reference to the drawings, as an example of a conventional semiconductor device in which electrodes on a semiconductor chip are electrically connected to conductive wires on a film base material via bumps.
FIG. 11 is a cross-sectional view showing a semiconductor device as an exemplary configuration of a conventional BOF. This semiconductor device, in which a semiconductor chip 1 is mounted on a tape carrier substrate 9 and the connection between the circuit side of the semiconductor chip 1 and the tape carrier substrate 9 is protected by a sealing resin 8, is used primarily as a driver for driving flat panel displays such as LCD displays.
The tape carrier substrate 9 has as its main elements a flexible insulating film base material 5, conductive wires 6 formed on a surface of the film base material 5, and bumps 14 provided on the conductive wires 6. The bumps 14 are formed on those conductive wires 6 on the film base material 5 that are disposed in positions opposed to electrodes 2 on the semiconductor chip 1. A metal plating film and a solder mask layer of insulating resin are formed on the conductive wires 6 as needed. Typically, polyimide is used as the film base material 5, and copper is used as the conductive wires 6.
To electrically connect the conductive wires 6 on the film base material 5 to the electrodes 2 on the semiconductor chip 1 via the bumps 14, the bumps 14 formed on the conductive wires 6 of the film base material 5 are bonded to the electrodes 2 of the semiconductor chip 1 by applying ultrasonic vibrations, for example, through the upper surface of the semiconductor chip.
With the above connection method in a conventional BOF, mechanical damage such as cracking is apt to be caused beneath the electrodes of the semiconductor chip, because the bumps formed on the conductive wires of the film base material are bonded directly to the electrodes of the semiconductor chip by applying ultrasonic vibrations to the semiconductor chip, as described above.